Su'aalo Tusaale ah oo ku saabsan Doodda Hirarka Raadiyaha
Mowjadaha raadiyaha waa nooc ka mid ah shucaaca elektromagnetic-ka ee ka shaqeeya isgaarsiinta bilaa-waayirka ah. Iyadoo ay jiraan mawjado u dhexeeya dhowr kilohertz (kHz) ilaa dhowr gigahertz (GHz), mowjadaha raadiyaha waxaa loo isticmaalaa codsiyo kala duwan - laga bilaabo baahinta raadiyaha iyo telefishanka ilaa nidaamyada isgaarsiinta gacanta. Maqaalkan, waxaan ka wada hadli doonnaa tusaalooyinka mowjadaha raadiyaha iyo sharraxaadahooda si ay nooga caawiyaan fahamka mabaadi'da iyo adeegsiga mowjadahaas nolol maalmeedka.
Su'aal Tusaale ah 1: Soo noqnoqoshada iyo Mowjadaha
Su'aal:
Raadiye ayaa gudbiya hirarka raadiyaha iyadoo la adeegsanayo xawaare dhan 100 MHz. Xisaabi hirarka. (Xawaaraha iftiinka waa 3 x 10^8 m/s.)
Dood:
Soo noqnoqoshada (f) iyo hirarka hirarka (λ) ee hirarka elektromagnetic-ka waxay la xiriiraan xawaaraha iftiinka (c) iyada oo loo marayo isla'egta:
\[ c = f \times \lambda \]
Halkee:
– \( c \) = xawaaraha iftiinka (3 x 10^8 m/s)
– \( f \) = soo noqnoqoshada (100 MHz ama 100 x 10^6 Hz)
– \( \lambda \) = hirarka hirarka (la heli karo)
Laga soo bilaabo isla'egta kore, hirarka dhererka waxaa lagu xisaabin karaa:
\[ \lambda = \frac{c}{f} \]
Markaa:
\[ \lambda = \frac{3 \times 10^8}{100 \times 10^6} = 3 \ \text{meter} \]
Markaa, mowjadda hirarka ee soo noqnoqda ee 100 MHz waa 3 mitir.
Su'aal Tusaale 2: Awoodda Gudbinta iyo Xoogga
Su'aal:
Gudbiye raadiye oo 50-watt ah ayaa hirarka raadiyaha si isku mid ah u sii daaya (si isku mid ah dhammaan jihooyinka). Xisaabi xoogga hirarka raadiyaha masaafada 10 mitir u jirta gudbiyaha.
Dood:
Xoogga (I) ee hirarka isotropic ahaan la sii daayo waxaa lagu xisaabin karaa:
\[ I = \frac{P}{A} \]
Halkee:
– \( P \) = awoodda gudbinta (50 watts)
– \( A \) = bedka dusha sare ee kubbada (4πr^2)
Masaafada (r) = 10 mitir, bedka dusha sare ee kubbadda waa:
\[ A = 4\pi (10)^2 = 400\pi \]
Markaa:
\[ I = \frac{50}{400\pi} = \frac{1}{8\pi} \ \text{watt/m}^2 \]
Markaa, xoojinta hirarka raadiyaha ee masaafada 10 mitir u jirta gudbiyaha waa \( \frac{1}{8\pi} \) watt/m².
Su'aal Tusaale ah 3: Ballaca iyo Awoodda Kanaalka
Su'aal:
Kanaalka isgaarsiintu wuxuu leeyahay ballaca xawaaraha 20 MHz. Haddii aad isticmaaleyso QPSK (Quadrature Phase Shift Keying), waa maxay awoodda ugu badan ee kanaalka?
Dood:
Qaab-dhismeedka QPSK wuxuu leeyahay 4 marxaladood oo kala duwan, sidaa darteed wuxuu gudbin karaa 2 bits calaamad kasta hal xilli.
Tirada calaamadaha ilbiriqsi kasta ee xawaaraha 20 MHz uu qaban karo waa:
\[ \text{Symbol} = 20 \jeer 10^6 \ \text{symbol/second} \]
Maadaama QPSK ay dirto 2 bits calaamaddiiba, awoodda ama tirada bits ilbiriqsigiiba (bitrate) waa:
\[ \text{Bitrate} = 20 \jeer 10^6 \jeer 2 = 40 \ \text{Mbps} \]
Sidaa darteed, awoodda ugu badan ee kanaalka waa 40 Mbps.
Su'aal Tusaale ah 4: Faragelinta iyo Khalkhalka
Su'aal:
Gudbiye raadiye oo ku shaqeeya xawaare dhan 101.1 MHz ayaa la kulma faragelin ka timaadda gudbiye kale oo ku shaqeeya xawaare dhan 101.3 MHz. Xisaabi inta jeer ee garaaca ka dhasha.
Dood:
Soo noqnoqoshada garaaca \( f_{beat} \) waxay dhacdaa sababtoo ah farqiga u dhexeeya laba soo noqnoqosho oo isku dhow waxaana lagu xisaabin karaa:
\[ f_{beat} = |f_1 – f_2| \]
Halkee:
– \( f_1 \) = 101.1 MHz
– \( f_2 \) = 101.3 MHz
Markaa:
\[ f_{beat} = |101.1 – 101.3| = | -0.2 | = 0.2 \ \qoraal{MHz} \]
Marka, soo noqnoqoshada garaaca natiijada waa 0.2 MHz.
Su'aal Tusaale ah 5: Saamaynta Doppler ee Hirarka Raadiyaha
Su'aal:
Raadiye ayaa ku gudbiya xawaare dhan 95 MHz. Diyaarad ayaa ku soo dhawaata saldhigga raadiyaha xawaare dhan 340 m/s. Xisaabi inta jeer ee diyaaradda ay hesho haddii xawaaraha hirarka raadiyaha uu la mid yahay xawaaraha iftiinka (3 x 10^8 m/s).
Dood:
Saamaynta Doppler ee hirarka raadiyaha waxaa lagu tilmaami karaa sidan soo socota:
\[ f_{accept} = f_{0} \left(\frac{c + v}{c}\right) \]
Halkee:
– \( f_0 \) = soo noqnoqoshada asalka ah (95 MHz)
– \( v \) = xawaaraha diyaaradda (340 m/s)
– \( c \) = xawaaraha hirarka (3 x 10^8 m/s)
Markaa:
\[ f_{accept} = 95 \jeer 10^6 \left(\frac{3 \jeer 10^8 + 340}{3 \jeer 10^8}\midig) \]
\[ f_{accept} = 95 \jeer 10^6 \left(\frac{3 \jeer 10^8 + 3.4 \jeer 10^2}{3 \jeer 10^8}\midig) \]
\[ f_{accept} \qiyaastii 95 \jeer 10^6 \left(1 + \frac{3.4 \jeer 10^2}{3 \jeer 10^8}\midig) \]
\[ f_{accept} \qiyaastii 95 \jeer 10^6 \left(1 + 1.1333 \jeer 10^{-6}\midig) \]
\[ f_{accept} \qiyaastii 95 \jeer 10^6 \jeer 1.0000011333 \]
\[ f_{accept} \qiyaastii 95.000107 \ \qoraal{MHz} \]
Markaa, inta jeer ee ay hesho diyaaradda soo socota waa qiyaastii 95.000107 MHz.
Xiritaanka
Fahmidda mabaadi'da aasaasiga ah iyo qaababka xisaabinta ee hirarka raadiyaha waa lama huraan qaybaha kala duwan ee injineernimada iyo sayniska. Dhibaatooyinka kor ku xusan waxay bixiyaan tusaalooyin ku saabsan sida fiisigiska hirarka raadiyaha loogu dabaqi karo xaalado kala duwan oo wax ku ool ah. Waddada loo maro faham qoto dheer waa iyada oo loo marayo ku celcelin joogto ah iyo sahaminta codsiyada dhabta ah ee hirarka raadiyaha ee tignoolajiyada isgaarsiinta ee aan isticmaalno maalin kasta.
